The Mysteries of the ELK M1G Databus

[iqvoice]

A few questions about the Elk M1G databus.

1) The instructions for the databus hub say to use the 568A wiring standard. However, I re-utilized some ethernet cables that already had tips on them with 568B standard. Does it matter as long as everything is attached right at the ends?

2) How many databus errors per day are acceptable or normal? I was getting about 1-2 per day, but since I added an external input expander and relay board, I'm getting more like 75-100 per day.

3) Assuming that the above is too many errors, what is the best way to go about testing the wiring? In my case, the total cable length is pretty short, probably not even 200 ft, even including there and back again. And all devices are visible. I'm confident that the ends are terminated properly But I'm concerned about long term reliability with so many errors being reported.

4) Some keypads are reporting more databus errors than other keypads... is this normal?

Thanks!

 

[pipeman]

Are you using a data bus hub?
Are you following the manual color coding at the keypads?
If 568B are used with jacks at both ends, it would not matter, but you will need to change the coding for flying ends.
Is the M1G terminated?
Are any or all of the keypads terminated?
Is the DBH terminated?

 

[iqvoice]

Are you using a data bus hub?
Are you following the manual color coding at the keypads?
If 568B are used with jacks at both ends, it would not matter, but you will need to change the coding for flying ends.
Is the M1G terminated?
Are any or all of the keypads terminated?
Is the DBH terminated?

Yes I'm using a data bus hub.
Can you explain what you mean by manual color coding?
Only the M1G and the data bus hub are terminated-- the M1G with a jumper and the hub with the included RJ45 terminating plug.

 

[pipeman]

If you had a 568B one ended cable, your green and orange pairs would be on different pins than what the Elk manuals show.
I'm less sure right now as to whether or not that will make a difference.

 

[pipeman]

Now, I've found something interesting that I don't understand, (yet), but may be part of your problem.
The Data Base Hub instruction sheet directs to use a crossover cable when connecting a second DBH to the first DBH.

I just realized a crossover cable is 568A on one end, and 568B on the other end.

 

[iqvoice]

Now, I've found something interesting that I don't understand, (yet), but may be part of your problem.
The Data Base Hub instruction sheet directs to use a crossover cable when connecting a second DBH to the first DBH.

I just realized a crossover cable is 568A on one end, and 568B on the other end.

Yeah, I saw that too. It made me wonder. Here's another unorthodox thing I did-- i wired two bus devices (a zone expander and a relay) off of one cable run from the databus hub. I figured this would be kosher, as long as I routed everything back properly to the hub. The circuit looks like this...

From databus hub, the A&B wires from cat6 are hooked to A&B screws on zone expander, pigtailed to two individual wires for A&B to connect the zone expander to the relay board, where I tie in to A1 and B1 from the cat6. When I disconnected the relay board, and just wired the zone expander like the instructions say (doh!) all the zone errors went away. So maybe it is a Really Bad Idea © to try to hook two devices to the bus with only one cat6 run from databus hub? I thought I would save time and effort by not running two cables...

 

[mustangcoupe]

looks like this can be accomplished with an DBHR but maybe not the DBH I am not sure see pages 12 and 13 of your M1 manual


http://www.elkproducts.com/pdf/M1_Installa...ming_Manual.pdf

 

[iqvoice]

looks like this can be accomplished with an DBHR but maybe not the DBH I am not sure see pages 12 and 13 of your M1 manual


http://www.elkproducts.com/pdf/M1_Installa...ming_Manual.pdf

Believe me, I've poured over every page of the manual. From what I can infer, with the DBHR, it's more like a star configuration then a bus, and you have to terminate every endpoint so you could end up with more than two terminating resistors, total. Looking at the DBH board, it appeared to be nothing more than solder lines connecting the A1's to A's and B1's to B's, so what difference would it make if I put two devices on the end of one cable? Yet it does seem to make a difference, unless I have some other cabling problem I haven't detected. Question: is the M1 G considered the master, and everything else on the bus is a slave?

I love the elk manuals, but you know there is a certain degree of "inside baseball". Some things, which once you understand the system become obvious, start off as very obscure for the newb.

The hours I spent puzzling over why sometimes my emails from the Ethernet Expander just seemed to disappear come to mind. That is until I comprehended that no emails except for test emails would ever be sent if I left myself connected to the Elk RP software! More like a bug then a feature....

 

[pipeman]

Whoa, whoa, whoa....

Now I'm worried big time.
I'm finishing up wiring a remote (250' one way , 500' round trip) detached garage.
I had full intentions of a single cat5 loop from the DBH to a keypad, with "local" branches to 2 (or more) expansion boards.
I did not expect any problems with that at all.

HEY ELK!!!

 

[mustangcoupe]

iqvoice if you get a bit please try to hook this back up. I agree it looks like it should work. if you can try a short piece of new cable.

 

[iqvoice]

iqvoice if you get a bit please try to hook this back up. I agree it looks like it should work. if you can try a short piece of new cable.

I'm going to try a few things tonight, including the use of new wire, and maybe a different hookup plan for the databus. I'll let you know what happens!

 

[iqvoice]

Okay, here is what I did:

1) Replaced the cat6 feed to the remote security box where I have the elk zone expander. Still lots of bus errors. 30+ errors over two hours.

2) Removed the cat6 feed from the data bus hub and instead connected it directly to the elk m1g. Removed the terminating jumper from the elk m1g and put it on the input expander, so now the m1g is in the middle of the bus, with the data bus hub to the "right" and the zone expander to the "left", so to speak. Less errors, but still generated 20+ bus errors over a two hour period.

3) Removed the zone expander from my remote box and instead installed an elk relay board by itself. Wrote an elk-rp program to switch one of the relays on and off over and over again, just to make sure that the relay board was generating "traffic" on the bus. Left it doing this over night, eight hours at least, zero bus errors in the morning!

4) Went to smarthome website, looked at reviews for elk zone expander and saw someone complaining about bus errors!!! Is this a common problem? That's why my first question in the first post was, "how many bus errors are normal?"

To be honest, I don't give a darn about bus errors--- I only got obsessed with them when the zone expander "disappeared" from the elk m1g shortly after i installed it, then reappeared, then disappeared, then reappeared. Subsequently, it has behaved-- but who wants an unreliable zone expander, even if it is only unreliable "once in a while!" So I started debugging and discovered the bus errors. This whole thing is making me very sad.

5) Ordered a second zone expander. Will see if it also causes problems. Hopefully not.

 

[AceCannon]

FWIW: Here is a somewhat dated pic of my patch panel (cable management has really not been implemented yet). All devices on my Elk databus are punched down to the bottom right of this panel using 568B, and I am using standard 0.5foot Monoprice patch cords to connect to the DBH on the wall to the right (yellow patch cables). The connections to the devices themselves are made using the exact method recommended in the M1G installation manual. I've looked into this and thought about it. . It does not make a difference if you use 568a or b since the orange and green are the only differences. These are the "out and back" conductors anyway.

This installation has been in place (with a few ongoing additions) for 1.5 months with no bus errors that I am aware of.

 

[pipeman]

I've looked into this and thought about it. . It does not make a difference if you use 568a or b since the orange and green are the only differences. These are the "out and back" conductors anyway.

That's what decided too, but...why would Elk direct to use a crossover cable when adding a second DBH?

Also, I'll be wiring my distant keypad, input and output expanders today.
I'm planning still on a series loop to and through the pigtails of each device and back to the DBH.

 

[AceCannon]

That's what decided too, but...why would Elk direct to use a crossover cable when adding a second DBH?

I dunno, but I'll be finding out at some point soon when I mount my second DBH and try it with a regular non-crossover patch cable.